Shoe sewing machine



Oct. 29, 1940. R MORRlLL 2,219,933

SHOE SEWING MACHINE Filed Dec. 23, 1938 Patented Oct. 29, 1940 UNITEDSTATES SHOE SEWING MACHINE Alfred R. Mfll'l'ill, Beverly, Mass., assignUnited Shoe'Machinery Corporation, Bo 'ugh of Flemington, N. J., acorporation of New Jersey Application December 23, 1938, Serial No.247,460

90laims.

The present invention relates to improvements in shoe sewing machines,and more particularly to improvements in thread handling devices adaptedfor use in inseam chain stitch sewing machines employing a curved hookneedle, 2.. looper, a take-up which acts to pull the thread with astitch setting strain around the shank of the needle while engaged withthe work, and a thread tensioning device which serves to assist thethread handling devices in the proper handling of the thread,particularly during the-operations of tightening and setting thestitches.

Applicant's invention is intended primarily as an improvement in thethread handling devices illustrated and described, for example, in hisprior Patent No. 1,971,575, dated August 28, 1934. The improvementconsists specifically in the provision of a tension control which actsduring the operation of the needle in tightening the preceding needleloop, to 'maintain a light tension on the thread, and then during thestitch setting stroke of the take-up, to produce a gradual in- ,creaseof the thread tension to cause the stitch to-be firmly set under thefull stitch setting 25 strain-without danger of breaking the thread.

Specifically, it is an object of the invention to provide an improvedthread tensioning device adapted for use in a machine of thisdescription, which will cause the thread handling devices to functionsmoothly and accurately to firmlyset each succeeding stitch, and whichwill operate equally Wellfor slow and for extremely high operatingspeeds of the machine.

It is a further object of the invention to provide a thread tensioningdevice including a tensionwheel and friction means acting on the tensionwheel to tension the thread, which will eliminate any harsh or jerkyaction in starting the wheel during the loop drawingstroke of the needleand during the stitch setting stroke of the take-up, and will at thesame time enable the take-up to set the stitch against a heavy tensionwhich may be regulated to the same maximum value consistent with thestrength of the thread and nature of the work beingoperated upon for awide range of operating speeds of the machine. While applicants improvedform of thread handling mechanism including a thread tension graduallyvariable from a minimum to amaximum value during movement of the take-uplever between its retracted position in which the loop drawing stroke ofthe needle is completed and its-advanced stitch setting position, hasthe advantage above stated, that adjustments of the tension by theoperator are rendered unnecessary over a wide range of operating speeds,such adjustment is nevertheless desirable to adapt the machine foroperation at extreme high speeds which may be in excess of 1000revolutions per minute. It is a further object of the invention toprovide a variable thread tension of this general description havingmeans for adjustment in which the tensioning device and the adjustingmeans associated therewith are so constructed and arranged as to providea correct proportional adjustment of the tension for each of its maximumand minimum values, whereby a tension of predetermined strength isplaced on the thread during the stitch setting stroke of the take-01flever, and a proportionally, lighter tension is placed on the threadduring the loop drawing stroke of the needle. I

It is still another object of the invention to provide an improvedtensioning device adapted for use in thread handling mechanism of thegeneral typereferred to, which will be extremely simple, and at the sametime efiective in operation to insure the formation of a tight regularseam.

With these and other objects in view as may hereinafter appear, aprincipal feature of the invention consists in the provision with athread handling mechanism of the general type referred to, including atensioning wheel, and frictioning means therefor, of means acting intimed relation to the movement of the take-up lever to graduallyincrease the strength of the friction from a relatively small to amaximum value as the take-up lever approaches the limit of itsstitch-setting stroke.

Another feature of the invention consists in the provision tin a machineof this general description, of which the thread handling mechanismincludes with a curved hook needle and a take-up, a thread tensiongradually variable from a minimum value for a position of the parts inwhich the loop drawing stroke of the needle is completed, to a maximumvalue as the take-up approaches its advanced stitch setting position, ofa calibrated expansible and contractible spring means for exerting saidvariable tension, and adjusting means cooperating therewithi wherebychanges in said adjustment will effect similarly proportionaladjustments of the pressures exerted by the spring in each of itsexpanded and contracted positions.

The several features of the invention consist also in the devices,combinations and arrangement of parts hereinafter described and claimed,

which together with the advantages to be-obtained thereby, will bereadily understood by one skilled inthe art from the followingdescription 4 taken in connection with the accompanying drawing, inwhich Fig. 1 is a view in left side elevation showing a portion ofthesewing head of a curved hook needle chainstitch sewing machine adaptedfor sewing together the inner solehnd upper, or sole, upper and welt,only so much of the machine being shown as is believed 1o necessary toillustrate the connection of the present invention therewith, thisfigure showing the parts in position with the needle substantially atthe limit of its retracting or loop drawing stroke; Fig. 2 is a viewsimilar to Fig. 1, but showing the parts in position at the limit of thestitch setting stroke of the take-up to set the stitch against the shankof the needle while engaged through the work; Fig. 3 is a detail planview of the tension wheel and friction brake mechanism associatedtherewith shown in Figs. 1 and 2; Fig. 4 is a detail plan view showingthe position of the needle and looper with the needle loop drawn throughthe work substantially in the position shown in Fig. 1; and Fig. 5 is adetail plan view showing the needle and looper in the positions taken inFig. 2, to illustrate the setting of the stitch against the needleshank, the subsequent position of the looper and thread after thelooping of a new bight of thread about the shank of the needle beingshown in this figure in dotand-dash lines.

The shoe machine illustrated in the drawing, is adapted for sewing theupper and the welt to the insole of a welt shoe, and is provided withthe usual operating elements of a welt sewing machine comprising acurved hook needle, a curved awl, a looper, a thread arm, a take-up, awelt guide, a channel guide, and a back rest.

The construction and operation of the stitch forming devices issubstantially the same as that described in applicant's prior PatentsNos. 1,920,998 and.1,971,575. The thread take-up and tensioningdevicesof the machine, the improvement in the control and operation of whichforms specifically the subject-matter of the present invention, exceptas hereinafter specifically set forth, are substantially similar to thatillustrated, for example, in the latter of the two prior patents abovementioned.

Referring specifically to the drawing, in which the several cooperatinginstrumentalities, for convenience of illustration, are given the samereference numbers as in the above-mentioned Patent No. 1,971,575, thecurved hook needle is desigu' nated at l, the awl at Ii, the looper at8,the thread finger at III, the take-up lever at I2, the welt guide atI4, the channel guide at I8, and the back rest at 20.

The operation of the thread handling devices 60 in the illustratedembodiment of the invention,

' difl'ers from the operation of those described and illustrated inapplicant's prior patents above noted, in that the auxiliary take-upaction of the take-up lever I2 is entirely eliminated, the takeup leverbeing at all times positively actuated by its operating cam, whichcomprises a closed cam track 2I formed in the usual cam disk 22, andinto which is fitted the cam roller 23 carried on the rear end of thetake-up lever I2. With this con- 70 struction and arrangement of thetake-up lever and its actuating cam, the take-up lever is movedpositively to its extreme loop setting position, and then positivelydownwardly to give up thread in timed relation to the operation of thethread finger, looper and needle.

The thread leading from the supply is tensloned as inthe patent abovereferred to, by means of a tension wheel I18, the thread being arrangedto pass over'the tension wheel I18 and thence downwardly around astationary thread truck 24, over 5 a thread truck 25 on the take-uplever I2, and thence downwardly through the,looper 8 to the work.Further, as in the construction above referred to, the, tension wheel I"is secured to a rotatable pin herein designated at 26 supported l0 in astationary bearing 28, and having also mounted thereon a friction drumI80. The parts of the thread tension as thus far described, areidentical with corresponding parts illustrated in the Morrill Patent No.1,971,575 above referred to. 15

In order that the application of the present invention thereto may bereadily understood, the mode of operation of the thread handlingmechanism employed, may be briefly stated as follows,-Beginning with theposition shown in Figs. 20 1 and 4, in which the needle has been movedto the limit of its withdrawing stroke to draw a new loop of needlethread 30 through the work, and in which the work has been advanced, theneedle is now advanced through the work to the position 25 shown in Fig.5, and the take-up lever I2 is moved positively under the influence ofits operating cam, to the fully raised position shown in Fig. 2, thuscausing the last loop of needle thread 30 to be pulled tightly againstthe shank of the needle 30 4, and a stitch setting strain to be exertedin the seam against the tension provided by the tension wheel I18, whichis at this time started sufficiently to draw off from the supply anamount of thread equal to that consumed in the forming of 35 theprevious stitch. Following this action of the take-up, the thread fingerIII is actuated to draw off a suflicient amount of thread between theneedle 4 and the previously formed stitch, so that reeving .of thethread through the needle hook 40 is prevented during the subsequentretracting or loop drawing stroke of the needle, and the looper isactuated to place the thread about the needle 4 as indicated indot-and-dash lines in Fig. 5.

During these operations, the take-up lever I2 is 45' moved downwardlygiving up thread. This downward movement is continued during theretracting movement -of the needle through the work. Slightly before theneedle reaches its fully retracted position, as shown in- Fig. 4, thedown- 50 ward movement of the take-up lever is arrested, causing the newneedle loop to be drawn tightly against the resistance provided by thethread tension, and causing the tension wheel I18 to be startedslightly. This loop drawing stroke of the 55 needle acts to tighten theloop 30 of the previously formed stitch around the two legs of the loopnow in the needle, duplicating the position of the parts shown in Fig.4.

It will be understood that while in the illusa yielding auxiliarytake-up action is employed.

With the usual construction and arrangement of the thread handlingdevices of these machines operating as above set forth, it has beencustom ary to employ. a thread tension of constant value 7 heretoforebeen customary, difficulty has been experienced in' securing anadjustment of the friction brake acting on the tension wheel I18 whichis adequate to insure the formation of a tight stitch without at thesame time causing thread breakage. Such thread breakage'is mostfrequently caused in high speed operation of the machine during thestitch setting stroke of the 'ation. invention, it is proposed to employa calibrated take-up lever by the relatively greater strain against orjerking of the thread required to start the tension wheel I18 againstthe continuously applied friction, the usual heavy and uniformly appliedthread tension tending to prevent the starting of the wheel I18 untilall of the thread employed in the making of the previous stitch is usedup, and as the take-up lever I2 approaches the limit of its upward orstitch setting stroke. In order to eliminate this difficulty, and at thesame time to provide a thread tension which .will be adequate to insurethe proper operation of the machine throughout the entire range ofoperating speeds, applicant proposes to employ a variable tension whichmay be graduated from a relatively small to a maximum value in directproportion as the take-up lever I2 moves from its low'to its high stitchsetting position.

With the form of thread handling mechanism herein specificallydescribed. in which the takee up lever is at all times positivelycontrolled. and in which it is proposed to adjust the operation of thecooperating parts to cause the needle loop to be drawn in against apreferably yielding tension supplied by the tension wheel, applicantsvariable thread tension is employed with advantage to produce therelatively lighter tension desirableduring the loop drawing stroke ofthe needle, and thereafter a gradually increasing tension during thestitch setting stroke of the take-up. In the illustrated construction,the variable tension desired is produced by the compression or expansionof a coil spring which is arranged to exert a frictionally engagingpressure on a friction brake, a simple adjustment being provided forpredetermining the amount of frictional pressure desired within thelimits of expansion and compression during machine oper- In accordancewith-one feature of the these pressures will, for example, increase theI pressures exerted to five and .ten pounds respectively.

In the illustrated embodiment of the invention, the brake shoe I82 isnivotallv mounted at. an nn 8. short lever arm 42 carried on a sleevehub 44 ona stationary pivot pin 48, and is urged against the frictiondrum I by means of a calibrated compression spring 48 seated at one endagainst a pin 48 on the take-up lever I2, and at its other end against acollar 58 on an adjustable set screw 52 screw-threaded into ahorizontally extending arm 64 formed on the sleeve hub 44. With thisconstruction it will readily be seen that the upward movement of thelever I2 will act to compress the spring 48, and thus to graduallyincrease the frictional pressure exerted by the friction shoe I82against the friction drum I88, the downwith the operation of the threadhandling devices above set forth as follows,-'the take-up lever I2moving downwardly to-give up thread with the retracting movement of theneedle through the work, reaches its extreme low position slightlybefore the needle finishes its loop drawing stroke,

so that the needle loop is finally drawn In against A the tensionprovided by the tension wheel I18,

this being the position of the parts shown in Figs. 1 and 4. For thisposition of the take-up lever I2, the spring 48 will have been moved toits fully expanded position, so that a relatively light braking frictionis exerted at this time upon the tension wheel I18. As the needle ismoved downwardly through the work to the position shown in Fig. 5, andas the take-up lever I2 starts its upward movement, the braking frictionon the tension wheel I18 is gradually increased. Under relatively slowspeed operating conditions of the machine. this gradual increase in thebraking pressure on the tension wheel I18 will be ade-- quate to preventpremature starting of the wheel I18, which will nevertheless be moregradually started as the take-up lever I2 approaches the extremely rapidupward movement of the takeup lever I2 introduces a new factor in thegreatly increased frictional resistance to the drawing in of the thread,and more particularly to the starting of the tension wheel I18 againstthe friction exerted by the brake shoe I82, the relatively lightfrictional strain exerted by the spring 48 during the earlier portionsof'the upward movement of the take-up lever I2, will permit a relativelyeasier starting of the tension wheel I18 which will take place moregradually and at a still earlier point in the upward movement of thetake-up lever I2. In any event the final setting of the stitch as thetake-up lever I2 reaches the limit of its upward movement, will takeplace against a maximum resistance of the thread tension. Under theseconditions, any tendency to the exerting of a sudden and excessivestrain on the thread or onthe work, through the operation of the threadhandling devices in setting the stitch, is avoided, and it becomespossible to per mit a relatively close adjustment of the tension exertedby the spring 46 to the desired maximum valm: inr the final aHhmanti-an" m r..u.. m...

.pressed position of the spring, in which the takeup lever i2 approachesthe limit of its upward or stitch setting stroke.

With this construction and mode of operation of the thread tension, itwill readily be seen that the strength of the thread tension againstwhich the stitch is set, is to a considerable extent independent of thespeed of operation of the machine, and may be adjusted by the operatorwith reference to the strength of the thread andthe requirements of thework being operated upon to produce uniform tight stitching, and with aminimum compensation for variations in inertia or other factorsintroduced by variations in the speed at which the machine is operated.

It will be understood that the invention is not limited to the specificembodiment shown, and that various deviations may be made therefromwithout departing from the spirit and scope of -H the appended claims.

What is claimed is: Y n

l. A chainstitch inseam shoe sewing machine having, in combination,thread handling devices including a curved hook needle, a looper, and aI take-up acting to pull the thread tightly around the needle whiletheneedle is.in the work, and to pull additional thread from-the supply,thread tensioning means, and means operative during the thread pullingmovement of the take-up to increase the tension applied against thethread by said tensioning means from a relatively small value to amaximum value as the take-up reaches the limit of its thread pullingmovement.

2. A chainstitch inseam shoe sewing machine the movement of the take-upto pull in the thread.

3. A chainstitch inseam shoe sewing machine having, in combination,thread handling devices including a curved hook needle, 8. looper, and atake-up acting to .pull the thread tightly around the needle whiletheneedle is in the work, and to pull additional thread from the supply, avariable thread tensioning means for tensioning the thread comprising atension wheel, and means actuated by said take-up and actingon s'aidvariable tensioning means during the thread pulling movement of thetake-upgto gradually increase the tension on the thread to a maximumvalue subsequent to the starting of the tension wheel in pulling threadfrom the supply;

' 4. A- chainstitch inseam shoe sewing machine having, in combination,thread handling devices including a curved hook needle movable to drawin a loop of needle thread, a looper, a thread a thread tensioning meansincluding a friction device, a spring connected between the frictiondevice and the take-up lever arranged during movement of the take-uplever in a take-up direction to gradually increase said friction, andduring movement in an opposite direction to gradually decrease saidfriction.

6. A chainstitch inseam shoe sewing machine having, in combination,thread handling devices including a curved hook needle, a looper, atakeup lever, and means for positively actuating the take-up lever togive up-thread to the looper and needle, and thereafter to pull thethread tightly around the needle while the needle is in the work, and topull additional thread from the supply, a thread tensioning-meansincluding a tension wheel and tensioning friction means acting thereon,and means to vary the frictional resistance exerted by said frictionmeans in timed relation to the movement of the take-up lever,constructed and arranged to reduce said frictional resistance to apredetermined minimum value during said thread giving motion of thetake-up lever, and thereafter to gradually increase said frictionalresistance to a predetermined maximum value at the limit of said threadpulling motion of-the take-up lever.

'7. A chainstitch inseam shoe sewing machine having, in combination,thread handling devices including a curvedhook needle, a looper, and atake-up lever movable to pull the thread tightly around the needle whilethe needle is in the work, a thread tensioning means including afriction device, a spring connected between the friction device and thetake-up lever arranged during movement of the take-up lever in a takeupdirection to gradually increase said friction, and during movement in anopposite direction to gradually decrease said friction betweenpredetermined maximum and minimum limits, and means for adjusting saidspring tension, said spring being calibrated so that adjustment thereofwill produce proportionately correct adjustments of both the minimum andmaximum values of the tension on the thread.

8. A chainstitch inseam shoe sewing machine having, in combination,thread handling devices including a curved hook needle, a looper, athread finger and a take-up movable to give up thread and thereafter topull the thread tightly around the needle while the needle is in thework, a

thread tensioning means including a friction device andan expansive andcontractible spring acting on said friction device, means acting on saidspring for controlling said thread tensioning'meansto-cause the needleto draw its loop ,against a minimum tension and thereafter to graduallyincrease the tension to a maximum value during the stitch setting strokeof the takeup lever, and means for'adjusting said spring to vary thetension exerted thereby, said spring being calibrated so that adjustmentthereof will produce proportional adjustments of both the maximumand-minimum values of the tension ment of the take-up to graduallyincrease the tension on the thread exerted by the thread tensioningdevice from a relatively small value and reaching a maximum valuesubsequent to the starting of the tensioning device by the take-up 6 inpulling thread from the supply.

ALFRED R. MORRILL.

